Generally, single-crystal silicon is pulled and manufactured from silicone melt stored in a vitreous silica crucible under high temperature. A rotary mold method is known as a method for manufacturing a vitreous silica crucible (Japanese Patent No. 1257513 (Japanese Unexamined Patent Application Publication No. 59-34659)). This method obtains a targeted crucible by depositing a predetermined thickness of silica powder on an inner surface of a hollow mold (bowl type) to rotate, melting and vitrifying this silica powder under high temperature by arc discharge, etc., forming the silica powder in the shape of a crucible along the inner surface of the mold, and removing the formed crucible after cooling.
An apparatus used for manufacture of the above vitreous silica crucible includes a heating furnace which houses a mold, and has a structure in which a supporting stand for arc electrodes is provided in an upper portion within the heating furnace, the arc electrodes are provided downward toward the inside of the mold in the middle of this supporting stand, and a silica powder layer deposited on the inner surface of the mold is heated and melted by arc discharge.
A predetermined thickness of silica powder as a raw material is deposited on an inner surface of a rotary mold, the mold on which the silica powder is deposited is housed in the heating furnace, the inside of the furnace is closed, and the silica powder is heated, melted, and vitrified by arc discharge while the mold is rotated, thereby manufacturing a vitreous silica crucible.